MySQL database _ database and data table operations

MySQL database

Command line connection

• Nowadays, terminals are basically not used to connect and operate databases in work. Generally, graphical tools, such as Navicat for MySQL, DBeaveretc., are used , but the command operation method of operating databases requires proficiency.

• Connect through the terminal. command:mysql -uroot / mysql -uroot -p (输入密码)

After the connection is successful, as shown in the figure below

sign out

quit 和 exit
或
ctrl+d

Database operation

• View all databases

show databases;

• Use database

use 数据库名;

• View the currently used database

select database();

• Create database

create database 数据库名 charset=utf8;
举例：
create database python charset=utf8;

• Delete database

drop database 数据库名;
例：
drop database python;

Data table operation

• View all tables in the current database

show tables;

• View table structure

desc 表名;

• Create table
  • auto_increment means automatic growth

CREATE TABLE table_name(
    column1 datatype contrai,
    column2 datatype,
    column3 datatype,
    .....
    columnN datatype,
    PRIMARY KEY(one or more columns)
);

例：创建班级表

create table classes(
    id int unsigned auto_increment primary key not null,
    name varchar(10)
);

例：创建学生表

create table students(
    id int unsigned primary key auto_increment not null,
    name varchar(20) default '',
    age tinyint unsigned default 0,
    height decimal(5,2),
    gender enum('男','女','人妖','保密'),
    cls_id int unsigned default 0
)

• Modify table-add fields

alter table 表名 add 列名 类型;
例：
alter table students add birthday datetime;

• Modify table-modify fields: renamed version

alter table 表名 change 原名 新名 类型及约束;
例：
alter table students change birthday birth datetime not null;

• Modify table-modify fields: not renamed version

alter table 表名 modify 列名 类型及约束;
例：
alter table students modify birth date not null;

• Modify table-delete field

alter table 表名 drop 列名;
例：
alter table students drop birthday;

• Delete table

drop table 表名;
例：
drop table students;

• View table creation statement

show create table 表名;
例：
show create table classes;